392 lines
12 KiB
Plaintext
392 lines
12 KiB
Plaintext
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HOWTO for the linux packet generator
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------------------------------------
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Enable CONFIG_NET_PKTGEN to compile and build pktgen either in-kernel
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or as a module. A module is preferred; modprobe pktgen if needed. Once
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running, pktgen creates a thread for each CPU with affinity to that CPU.
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Monitoring and controlling is done via /proc. It is easiest to select a
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suitable sample script and configure that.
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On a dual CPU:
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ps aux | grep pkt
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root 129 0.3 0.0 0 0 ? SW 2003 523:20 [pktgen/0]
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root 130 0.3 0.0 0 0 ? SW 2003 509:50 [pktgen/1]
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For monitoring and control pktgen creates:
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/proc/net/pktgen/pgctrl
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/proc/net/pktgen/kpktgend_X
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/proc/net/pktgen/ethX
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Tuning NIC for max performance
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==============================
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The default NIC settings are (likely) not tuned for pktgen's artificial
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overload type of benchmarking, as this could hurt the normal use-case.
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Specifically increasing the TX ring buffer in the NIC:
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# ethtool -G ethX tx 1024
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A larger TX ring can improve pktgen's performance, while it can hurt
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in the general case, 1) because the TX ring buffer might get larger
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than the CPU's L1/L2 cache, 2) because it allows more queueing in the
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NIC HW layer (which is bad for bufferbloat).
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One should hesitate to conclude that packets/descriptors in the HW
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TX ring cause delay. Drivers usually delay cleaning up the
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ring-buffers for various performance reasons, and packets stalling
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the TX ring might just be waiting for cleanup.
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This cleanup issue is specifically the case for the driver ixgbe
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(Intel 82599 chip). This driver (ixgbe) combines TX+RX ring cleanups,
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and the cleanup interval is affected by the ethtool --coalesce setting
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of parameter "rx-usecs".
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For ixgbe use e.g. "30" resulting in approx 33K interrupts/sec (1/30*10^6):
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# ethtool -C ethX rx-usecs 30
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Kernel threads
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==============
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Pktgen creates a thread for each CPU with affinity to that CPU.
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Which is controlled through procfile /proc/net/pktgen/kpktgend_X.
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Example: /proc/net/pktgen/kpktgend_0
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Running:
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Stopped: eth4@0
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Result: OK: add_device=eth4@0
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Most important are the devices assigned to the thread.
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The two basic thread commands are:
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* add_device DEVICE@NAME -- adds a single device
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* rem_device_all -- remove all associated devices
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When adding a device to a thread, a corrosponding procfile is created
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which is used for configuring this device. Thus, device names need to
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be unique.
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To support adding the same device to multiple threads, which is useful
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with multi queue NICs, a the device naming scheme is extended with "@":
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device@something
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The part after "@" can be anything, but it is custom to use the thread
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number.
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Viewing devices
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===============
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The Params section holds configured information. The Current section
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holds running statistics. The Result is printed after a run or after
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interruption. Example:
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/proc/net/pktgen/eth4@0
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Params: count 100000 min_pkt_size: 60 max_pkt_size: 60
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frags: 0 delay: 0 clone_skb: 64 ifname: eth4@0
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flows: 0 flowlen: 0
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queue_map_min: 0 queue_map_max: 0
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dst_min: 192.168.81.2 dst_max:
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src_min: src_max:
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src_mac: 90:e2:ba:0a:56:b4 dst_mac: 00:1b:21:3c:9d:f8
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udp_src_min: 9 udp_src_max: 109 udp_dst_min: 9 udp_dst_max: 9
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src_mac_count: 0 dst_mac_count: 0
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Flags: UDPSRC_RND NO_TIMESTAMP QUEUE_MAP_CPU
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Current:
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pkts-sofar: 100000 errors: 0
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started: 623913381008us stopped: 623913396439us idle: 25us
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seq_num: 100001 cur_dst_mac_offset: 0 cur_src_mac_offset: 0
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cur_saddr: 192.168.8.3 cur_daddr: 192.168.81.2
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cur_udp_dst: 9 cur_udp_src: 42
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cur_queue_map: 0
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flows: 0
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Result: OK: 15430(c15405+d25) usec, 100000 (60byte,0frags)
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6480562pps 3110Mb/sec (3110669760bps) errors: 0
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Configuring devices
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===================
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This is done via the /proc interface, and most easily done via pgset
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as defined in the sample scripts.
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Examples:
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pgset "clone_skb 1" sets the number of copies of the same packet
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pgset "clone_skb 0" use single SKB for all transmits
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pgset "burst 8" uses xmit_more API to queue 8 copies of the same
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packet and update HW tx queue tail pointer once.
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"burst 1" is the default
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pgset "pkt_size 9014" sets packet size to 9014
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pgset "frags 5" packet will consist of 5 fragments
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pgset "count 200000" sets number of packets to send, set to zero
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for continuous sends until explicitly stopped.
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pgset "delay 5000" adds delay to hard_start_xmit(). nanoseconds
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pgset "dst 10.0.0.1" sets IP destination address
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(BEWARE! This generator is very aggressive!)
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pgset "dst_min 10.0.0.1" Same as dst
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pgset "dst_max 10.0.0.254" Set the maximum destination IP.
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pgset "src_min 10.0.0.1" Set the minimum (or only) source IP.
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pgset "src_max 10.0.0.254" Set the maximum source IP.
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pgset "dst6 fec0::1" IPV6 destination address
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pgset "src6 fec0::2" IPV6 source address
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pgset "dstmac 00:00:00:00:00:00" sets MAC destination address
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pgset "srcmac 00:00:00:00:00:00" sets MAC source address
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pgset "queue_map_min 0" Sets the min value of tx queue interval
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pgset "queue_map_max 7" Sets the max value of tx queue interval, for multiqueue devices
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To select queue 1 of a given device,
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use queue_map_min=1 and queue_map_max=1
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pgset "src_mac_count 1" Sets the number of MACs we'll range through.
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The 'minimum' MAC is what you set with srcmac.
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pgset "dst_mac_count 1" Sets the number of MACs we'll range through.
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The 'minimum' MAC is what you set with dstmac.
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pgset "flag [name]" Set a flag to determine behaviour. Current flags
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are: IPSRC_RND # IP source is random (between min/max)
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IPDST_RND # IP destination is random
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UDPSRC_RND, UDPDST_RND,
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MACSRC_RND, MACDST_RND
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TXSIZE_RND, IPV6,
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MPLS_RND, VID_RND, SVID_RND
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FLOW_SEQ,
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QUEUE_MAP_RND # queue map random
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QUEUE_MAP_CPU # queue map mirrors smp_processor_id()
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UDPCSUM,
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IPSEC # IPsec encapsulation (needs CONFIG_XFRM)
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NODE_ALLOC # node specific memory allocation
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NO_TIMESTAMP # disable timestamping
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pgset spi SPI_VALUE Set specific SA used to transform packet.
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pgset "udp_src_min 9" set UDP source port min, If < udp_src_max, then
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cycle through the port range.
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pgset "udp_src_max 9" set UDP source port max.
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pgset "udp_dst_min 9" set UDP destination port min, If < udp_dst_max, then
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cycle through the port range.
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pgset "udp_dst_max 9" set UDP destination port max.
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pgset "mpls 0001000a,0002000a,0000000a" set MPLS labels (in this example
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outer label=16,middle label=32,
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inner label=0 (IPv4 NULL)) Note that
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there must be no spaces between the
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arguments. Leading zeros are required.
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Do not set the bottom of stack bit,
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that's done automatically. If you do
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set the bottom of stack bit, that
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indicates that you want to randomly
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generate that address and the flag
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MPLS_RND will be turned on. You
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can have any mix of random and fixed
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labels in the label stack.
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pgset "mpls 0" turn off mpls (or any invalid argument works too!)
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pgset "vlan_id 77" set VLAN ID 0-4095
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pgset "vlan_p 3" set priority bit 0-7 (default 0)
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pgset "vlan_cfi 0" set canonical format identifier 0-1 (default 0)
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pgset "svlan_id 22" set SVLAN ID 0-4095
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pgset "svlan_p 3" set priority bit 0-7 (default 0)
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pgset "svlan_cfi 0" set canonical format identifier 0-1 (default 0)
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pgset "vlan_id 9999" > 4095 remove vlan and svlan tags
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pgset "svlan 9999" > 4095 remove svlan tag
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pgset "tos XX" set former IPv4 TOS field (e.g. "tos 28" for AF11 no ECN, default 00)
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pgset "traffic_class XX" set former IPv6 TRAFFIC CLASS (e.g. "traffic_class B8" for EF no ECN, default 00)
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pgset stop aborts injection. Also, ^C aborts generator.
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pgset "rate 300M" set rate to 300 Mb/s
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pgset "ratep 1000000" set rate to 1Mpps
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pgset "xmit_mode netif_receive" RX inject into stack netif_receive_skb()
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Works with "burst" but not with "clone_skb".
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Default xmit_mode is "start_xmit".
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Sample scripts
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==============
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A collection of tutorial scripts and helpers for pktgen is in the
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samples/pktgen directory. The helper parameters.sh file support easy
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and consistant parameter parsing across the sample scripts.
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Usage example and help:
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./pktgen_sample01_simple.sh -i eth4 -m 00:1B:21:3C:9D:F8 -d 192.168.8.2
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Usage: ./pktgen_sample01_simple.sh [-vx] -i ethX
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-i : ($DEV) output interface/device (required)
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-s : ($PKT_SIZE) packet size
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-d : ($DEST_IP) destination IP
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-m : ($DST_MAC) destination MAC-addr
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-t : ($THREADS) threads to start
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-c : ($SKB_CLONE) SKB clones send before alloc new SKB
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-b : ($BURST) HW level bursting of SKBs
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-v : ($VERBOSE) verbose
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-x : ($DEBUG) debug
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The global variables being set are also listed. E.g. the required
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interface/device parameter "-i" sets variable $DEV. Copy the
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pktgen_sampleXX scripts and modify them to fit your own needs.
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The old scripts:
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pktgen.conf-1-2 # 1 CPU 2 dev
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pktgen.conf-1-1-rdos # 1 CPU 1 dev w. route DoS
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pktgen.conf-1-1-ip6 # 1 CPU 1 dev ipv6
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pktgen.conf-1-1-ip6-rdos # 1 CPU 1 dev ipv6 w. route DoS
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pktgen.conf-1-1-flows # 1 CPU 1 dev multiple flows.
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Interrupt affinity
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===================
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Note that when adding devices to a specific CPU it is a good idea to
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also assign /proc/irq/XX/smp_affinity so that the TX interrupts are bound
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to the same CPU. This reduces cache bouncing when freeing skbs.
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Plus using the device flag QUEUE_MAP_CPU, which maps the SKBs TX queue
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to the running threads CPU (directly from smp_processor_id()).
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Enable IPsec
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============
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Default IPsec transformation with ESP encapsulation plus transport mode
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can be enabled by simply setting:
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pgset "flag IPSEC"
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pgset "flows 1"
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To avoid breaking existing testbed scripts for using AH type and tunnel mode,
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you can use "pgset spi SPI_VALUE" to specify which transformation mode
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to employ.
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Current commands and configuration options
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==========================================
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** Pgcontrol commands:
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start
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stop
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reset
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** Thread commands:
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add_device
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rem_device_all
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** Device commands:
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count
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clone_skb
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burst
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debug
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frags
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delay
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src_mac_count
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dst_mac_count
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pkt_size
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min_pkt_size
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max_pkt_size
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queue_map_min
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queue_map_max
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skb_priority
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tos (ipv4)
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traffic_class (ipv6)
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mpls
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udp_src_min
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udp_src_max
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udp_dst_min
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udp_dst_max
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node
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flag
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IPSRC_RND
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IPDST_RND
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UDPSRC_RND
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UDPDST_RND
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MACSRC_RND
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MACDST_RND
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TXSIZE_RND
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IPV6
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MPLS_RND
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VID_RND
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SVID_RND
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FLOW_SEQ
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QUEUE_MAP_RND
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QUEUE_MAP_CPU
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UDPCSUM
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IPSEC
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NODE_ALLOC
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NO_TIMESTAMP
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spi (ipsec)
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dst_min
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dst_max
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src_min
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src_max
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dst_mac
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src_mac
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clear_counters
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src6
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dst6
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dst6_max
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dst6_min
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flows
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flowlen
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rate
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ratep
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xmit_mode <start_xmit|netif_receive>
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vlan_cfi
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vlan_id
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vlan_p
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svlan_cfi
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svlan_id
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svlan_p
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References:
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ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/
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ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/examples/
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Paper from Linux-Kongress in Erlangen 2004.
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ftp://robur.slu.se/pub/Linux/net-development/pktgen-testing/pktgen_paper.pdf
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Thanks to:
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Grant Grundler for testing on IA-64 and parisc, Harald Welte, Lennert Buytenhek
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Stephen Hemminger, Andi Kleen, Dave Miller and many others.
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Good luck with the linux net-development.
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